" DISCLAIMER: The ILO does not take responsibility for content presented on this web portal that is presented in any language other than English, which is the language used for the initial production and peer-review of original content. Certain statistics have not been updated since the production of the 4th edition of the Encyclopaedia (1998)."

Tuesday, 15 February 2011 18:55

Case Study: Exposure Standards in Russia

Written by
Rate this item
(1 Vote)

Comparison of the Philosophical Bases of Maximum Allowable Concentrations (MACs) and Threshold Limit Values (TLVs)

Rapid development of chemistry and wide usage of chemical products require specific toxicological studies and hazards evaluation with regard to long-term and combined effects of chemical substances. The setting of standards for chemicals in the working environment is being conducted by occupational hygienists in many countries of the world. Experience on the matter has been accumulated in international and multilateral organizations such as the International Labour Organization, the World Health Organization, the United Nations Environment Programme, the Food and Agriculture Organization and the European Union.

Much has been done in this field by Russian and American scientists. In 1922 studies were launched in Russia to set up standards for chemicals in the air of indoor work areas, and the first maximum allowable concentration (MAC) value for sulphur-containing gas was adopted. By 1930 only 12 MAC values were established, whereas by 1960 their number reached 181.

The American Conference of Governmental Industrial Hygienists (ACGIH) started its work in 1938, and the first threshold limit values (TLVs) list was published in 1946 for 144 substances. The TLVs are to be interpreted and used only by the specialists in this field. If a TLV has been included in the safety standards (the so-called standards of national consensus) and the federal standards, it becomes legal.

At present more than 1,500 MAC values have been adopted for workplace air in Russia. More than 550 TLVs for chemical substances have been recommended in the United States.

Analysis of hygienic standards made in 1980–81 showed that 220 chemicals of the MAC list (Russia) and the TLV list (United States) had the following differences: from two- to fivefold differences were found in 48 substances (22%), 42 substances had five- to ten-fold differences, and 69% substances (31%) had more than ten-fold differences. Ten per cent of the recommended TLVs were 50 times higher than the MAC values for the same substances. The MAC values, in turn, were higher than the TLVs for 16 substances.

The largest divergence of standards occurs in the class of chlorinated hydrocarbons. Analysis of the TLV list adopted in 1989–90 showed a trend toward a reduction of the earlier recommended TLVs compared with the MAC values for chlorinated hydrocarbons and some solvents. Differences among the TLVs and the MACs for the majority of metal aerosols, metalloids, and their compounds were insignificant. The divergences for irritant gases were also slight. The TLVs for lead, manganese and tellurium compared with their MAC analogues disagreed 15, 16 and 10 times, respectively. The differences for acetic aldehyde and formaldehyde were the most extreme—36 and 6 times, respectively. In general, the MAC values adopted in Russia are lower than the TLVs recommended in the United States.

These divergences are explained by the principles used in the development of hygienic standards in the two countries and by the way of these standards are applied to protect workers’ health.

A MAC is a hygienic standard used in Russia to denote a concentration of a harmful substance in the air of the workplace which will not cause, in the course of work for eight hours daily or for any other period of time (but not more than 41 hours per week throughout the working life of an individual), any disease or deviation in the health status as detectable by the available methods of investigation, during the working life or during the subsequent life of the present and next generations. Thus, the concept used in defining the MAC does not allow for any adverse effect on a worker or his or her progeny. The MAC is a safe concentration.

A TLV is the concentration (in air) of a material to which most workers can be exposed daily without adverse effect. These values are established (and revised annually) by the ACGIH and are time-weighted concentrations for a seven- or eight-hour workday and 40-hour workweek. For most materials the value may be exceeded, to a certain extent, provided there are compensatory periods of exposure below the value during the workday (or in some cases the week). For a few materials (mainly those that produce a rapid response) the limit is given as ceiling concentration (i.e., a maximum allowable concentration) that should never be exceeded. The ACGIH states that TLVs should be used as guides in the control of health hazards, and are not fine lines between safe and dangerous concentrations, nor are they a relative index of toxicity.

The TLV definition also contains the principle of inadmissibility of harmful impact. However, it does not cover all of the working population, and it is admitted that a small percentage of workers may manifest health changes or even occupational pathologies. Thus TLVs are not safe for all workers.

According to ILO and WHO experts, these divergences are the result of different scientific approaches to a number of interrelated factors including the definition of an adverse health effect. Therefore, different initial approaches for the control of chemical hazards lead to different methodological principles, essential points of which are presented below.

The main principles of setting hygienic standards for dangerous substances in the air of workplaces in Russia compared with those in the United States are summarized in table 1. Of special importance is the theoretical concept of the threshold, the basic difference between the Russian and the American specialists that underlies their approaches to setting standards. Russia accepts the concept of a threshold for all types of dangerous effects of chemical substances.

Table 1. A comparison of some ideological bases for Russian and American standards

Russia (MACs)

United States (TLVs)

Threshold nature of all kinds of adverse effects. Changes of specific and non-specific factors regarding the criteria of harmful impact are evaluated.

No recognition of threshold for mutagens and some carcinogens. Changes of specific and non-specific factors depending on “dose-effect ”and “dose-response” relationship are evaluated.

Priority of medical and biological factors over technological and economic criteria.

Technological and economic criteria prevail.

Prospective toxicological assessment and interpretation of standards before the commercialization of chemical products.

Retrospective setting of standards.


However, the recognition of a threshold for some types of effects  requires  the  distinction  between  injurious  and  non-injurious effects produced by chemical substances. Consequently, the threshold of unhealthy effects established in Russia is the minimal concentration (dose) of a chemical that causes changes beyond the limits of physiological adaptive responses or produces latent (temporarily compensated) pathologies. In addition, various statistical, metabolic, and toxico-kinetic criteria of adverse effects of chemicals are used to differentiate between the processes of physiological adaptation and pathological compensation. Pathomorphological changes and narcotic symptoms of earliest impairment have been suggested in the United States for the identification of injurious and non-injurious effects. It means that more sensitive methods have been chosen for the toxicity evaluation in Russia than those in the United States. This, therefore, explains the generally lower levels of MACs compared to TLVs. When the detection criteria for injurious and non-injurious effects of chemicals are close or practically coincide, as in the case of irritant gases, the differences in standards are not so significant.

The evolution of toxicology has put into practice new methods for the identification of minor changes in tissues. These are enzyme induction in the smooth endoplastic reticular hepatic tissue and reversible hypertrophy of the liver. These changes may appear after exposure to low concentrations of many chemical substances. Some researchers consider these to be adaptive reactions, while others interpret them as early impairments. Today, one of the most difficult tasks of toxicology is obtaining data that show whether enzyme disturbances, nervous system disorders and changes in behavioural responses are the result of deteriorated physiological functions. This would make it possible to predict more serious and/or irreversible impairments in case of long-term exposure to dangerous substances.

Special emphasis is placed on the differences in the sensitivity of methods used for the establishment of MACs and TLVs. Very sensitive methods of conditioned reflexes applied to studies of the nervous system in Russia have been found to be the main cause of divergences between the MACs and the TLVs. However, the use of this method in the process of hygienic standardization is not obligatory. Numerous methods of different sensitivities are normally used for the developing of a hygienic standard.

A great number of studies conducted in the United States in connection with the setting-up of exposure limits are aimed at examining the transformation of industrial compounds in the human body (routes of exposure, circulation, metabolism, removal, etc.). Methods of chemical analysis used to establish the values of TLVs and MACs also cause divergences due to their different selectivities, accuracies and sensitivities. An important element usually taken into consideration by OSHA in the standardization process in the United States is the “technical attainability” of a standard by industry. As a result, some standards are recommended on a basis of the lowest presently existing concentrations.

MAC values in Russia are established on a basis of the prevalence of medico-biological characteristics, whereas the technological attainability of a standard is practically ignored. This partly explains lower MAC values for some chemical substances.

In Russia MAC values are assessed in toxicological studies before a substance is authorized for industrial use. A tentative safe exposure level is established during the laboratory synthesis of a chemical. The MAC value is established after animal experiments, at the design stage of the industrial process. The correction of the MAC value is carried out after evaluation of working conditions and workers’ health when the substance is used in industry. Most of the safe levels of exposure in Russia have been recommended after experiments on animals.

In the United States a final standard is established after a chemical substance has been introduced in industry, because the values of permissible levels of exposure are based on the assessment of health. As long as the differences of principle between the MACs and the TLVs remain, it is unlikely to expect the convergence of these standards in the near future. However, there is a trend towards the reduction of some TLVs that makes this not so impossible as it may seem.



Read 3552 times Last modified on Saturday, 16 July 2011 16:37


Part I. The Body
Part II. Health Care
Part III. Management & Policy
Development, Technology, and Trade
Disability and Work
Education and Training
Ethical Issues
Labour Relations and Human Resource Management
Resources: Information and OSH
Resources, Institutional, Structural and Legal
Community level
Regional and National Examples
International, Government and Non-Governmental Safety and Health
Topics In Workers Compensation Systems
Work and Workers
Worker's Compensation Systems
Part IV. Tools and Approaches
Part V. Psychosocial and Organizational Factors
Part VI. General Hazards
Part VII. The Environment
Part VIII. Accidents and Safety Management
Part IX. Chemicals
Part X. Industries Based on Biological Resources
Part XI. Industries Based on Natural Resources
Part XII. Chemical Industries
Part XIII. Manufacturing Industries
Part XIV. Textile and Apparel Industries
Part XV. Transport Industries
Part XVI. Construction
Part XVII. Services and Trade
Part XVIII. Guides

Resources: Institutional, Structural and Legal Additional Resources

Click the Button below to view additional resources for this topic.


Resources: Institutional, Structural and Legal References

African (Banjul) Charter On Human and People’s Rights. 1982. Document No. 21 ILM 59. Adopted 27 June, 1981.

Alston, P. 1984. Conjuring up new human rights: A proposal for quality control. Am J Int Law 78:607-621.

Commission of the European Communities. 1990. Health and safety at work in the European Community, Social Europe.

Corn, JK. 1992. Response to Occupational Health Hazards: A Historical Perspective. New York: Van Nostrand Reinhold.

Corn, M. 1985. Preventing Injury and Illness in the Workplace. Washington, DC: US Government Printing Office.

European Social Charter. 1994. Signed by the Council of Europe on 18 October 1961. Entered into force on 26 February 1965. In Twenty-Five Human Rights Documents. New York: Columbia Univ. Centre for Study of Human Rights.

Faden, R. 1985. Reproductive Health Hazards in the Workplace. Washington, DC: US Government Printing Office.

Feitshans, IL. 1993. Designing an Effective OSHA Compliance Program. Deerfield, Ill.: Boardman Callaghan.

—. 1994. Job security for pregnant employees: The model employment termination act. Ann Am Acad Polit SS 119 (November).

Food and Agriculture Organization (FAO). 1985. International Code of Conduct on the Distribution and Use of Pesticides.

Friedman, W. 1969. International Law: Cases and Materials. New York: American Casebook Series.

Grad, FP and IL Feitshans. 1992. Article 12: Right to health. In US Ratification of the International Covenants On Human Rights, edited by H Hannum and D Fischer. Washington, DC: American Society of International Law.

Henkin, L. 1990. International law: Politics, values and functions. General course on public international law. In Academy of International Law Offprint of Collected Courses. Vol. 216. Dordrecht: Martinus Nijhoff.

Henkin, L and JL Hargrove (eds.). 1992. Human Rights: An Agenda for the Next Century. American Society of International Law.

International Atomic Energy Agency (IAEA). 1994. International Standards for Protection against Ionizing Radiation and the Safety of Radiation Sources. Vienna: IAEA.

International Convention on The Elimination of All Discrimination Against Women. 1979. Document no. ILM. 33, 12 and 28 ILM 1446, Arts. 6 and 27. Adopted 18 December 1979.

International Covenant on Economic, Social and Cultural Rights (ICESCR). 1994. In Twenty-Five Human Rights Documents. New York: Columbia Univ. Centre for Study of Human Rights.

International Labour Organization (ILO). 1984. Improving Working Conditions and Environment: An International Programme (PIACT). Geneva: ILO.

—. 1990. International Directory of Occupational Safety and Health Services and Institutions. Occupational Safety and Health Series, No. 66. Geneva: ILO.

—. 1991. Prevention of Major Industrial Accidents. An ILO code of practice. Geneva: ILO.

—. 1991. Occupational Exposure Limits for Airborne Toxic Substances. Occupational Safety and Health Series, No. 37. Geneva: ILO.

—. 1992. Constitution of the International Labour Organization and Standing Orders of the International Labour Conference. Geneva: ILO.

—.1993. Protection of Workers from Power Frequency Electric and Magnetic Fields. Occupational Safety and Health Series, No. 69. Geneva: ILO.

—. 1996a. International Labour Conventions and Recommendations, 1919-1951 (vol. 1), 1952-1976 (vol. 2), 1977-1995 (vol. 3). Geneva: ILO.

—. 1996b. Recording and Notification of Occupational Accidents and Diseases. An ILO code of practice. Geneva: ILO.

—. 1996. Accident Prevention on Board Ship at Sea and in Port. An ILO code of practice. Geneva: ILO.

—. 1996c. Management of Alcohol and Drug-related Issues in the Workplace. An ILO code of practice. Geneva: ILO.

Johnston, A. 1970. The International Labour Organization: Its Work for Social and Economic Progress. London: Europa Publications.

Mausner, JS and S Kramer. 1985. Epidemiology: An Introductory Text. Philadelphia: WB Saunders.

Morgenstern, F. 1982. Deterrence and Compensation: Legal Liability in Occupational Safety and Health. Geneva: ILO.

Nightingale, E. 1990. Genetic Monitoring and Screening in the Workplace. Geneva, ILO.

Pan-American Health Organization (PAHO). 1980. Official document No. 173. Washington, DC: PAHO.

—. 1990. Resolution XIV on Workers’ Health, the 23rd Pan-American Sanitary Conference.

Parmeggiani, L (ed.). 1983. Encyclopaedia of Occupational Health and Safety. Geneva: ILO.

Ransom v. Sir Robert McAlpine and Sons Ltd. 1971. Queen’s Bench Division, 12 March 1971.

Rothstein, M. 1984. Medical Screening of Workers. Washington, DC: Bureau of National Affairs (BNA).

Ruda, JM. 1994. Those who turn principles into reality. World Work Mag ILO (10) (December).

Samsom, KT. 1984. The changing pattern of ILO supervision. Int Labour Rev 569.

Sigler, JA and JE Murphy. 1988. Interactive Corporate Compliance: An Alternative to Regulatory Compulsion. New York: Quorum Books.

Stellman, J and S Daum. 1973. Work Is Dangerous to Your Health. New York: Pantheon Books.

Summers, C. 1992. Article 7. In US Ratification of the International Covenants On Human Rights, edited by H Hannum and D Fischer. Washington, DC: American Society of International Law.

TUTB. 1991. Synopsis of European Health and Safety Directive.

United Nations. 1994. United Nations Charter, signed 26 June, 1945, entered into force 24 October, 1945. In Twenty-Five Human Rights Documents. New York: Columbia Univ. Center for Study of Human Rights.

United Nations Department of Public Information. 1992. Basic Facts About the United Nations. New York: UN.

United Nations General Assembly. 1994. Universal Declaration of Human Rights (UDHR), United Nations General Assembly resolution 217A (II) on 10 December 1948. In Twenty-Five Human Rights Documents. New York: Columbia Univ. Center for Study of Human Rights.

Virginia Workmens’ Compensation Act Annotated. 1982. Sec. 65. 1-7. Charlottesville, Va: Michie.

Weeks, JL, BS Levy, and GR Wagner. 1991. Preventing Occupational Disease and Injury. Washington, DC: American Public Health Association (APHA).

World Bank. 1974. Environmental, Health and Human Ecologic Considerations in Economic Development Projects.

—. 1993a. The World Bank and the Environment, Fiscal 1993. World Bank: Oxford University Press.

—. 1993b. World Development Report 1993, Investing in Health. World Bank: Oxford University Press.

World Health Organization (WHO). 1978. Constitution of the World Health Organization. In Basic Documents. Geneva: WHO.

—. 1978. Declaration of Alma-Ata. International Conference on Primary Health Care, 6 to 12 September 1978, Alma-Ata, USSR.

Wright v. Dunlop Rubber Co. and another. 1971. Queen’s Bench Division, 21 April 1971.